Skin Infections, Infestations and Drug Eruptions Flashcards
What is scabies
High contagious infestation by the mite Sarcoptes Sacbiei. Spread is via direct contact.
What is the pathophysiology of scabies
Female mite digs a burrow that looks like a short wavy, grey or red lines on the skin surface
Here she lays eggs which hatch as larvae. The itch and red rash that follows occurs due to allergic sensitivity to the larvae 30 days later delayed type IV hypersensitivity reaction.
How does scabies present?
Papules, vesicles, pustules and nodules affecting finger webs, wrist, flexures, axillae, abdomen (especially waistband and umbilicus), buttocks and groins
Secondary features such as excoriation and infection occur due to scratching
Who needs to be treated after a scabies infection?
Treat all members of the household and all close contacts even if asymptomatic and avoid physical contact with others until treatment complete
What are the management options for scabies?
First line – Permethrin 5% dermal cream – safe in pregnancy
Second line – Malathion 0.5% is second line – not safe in pregnancy
Oral ivermectin if severe such as crusted (Norwegian) scabies
Rash and itch take 4-6 weeks to settle – anti-pruritic cream crotamiton can be useful in this time
What advice should you give regarding the applying of creams/ointments for scabies?
Take a warm bath with soap all over the skin
Scrub finger nails with a firm brush
Apply cream given for treatment all over body (contrary to manufacturers advice) paying particular attention to between skin folds e.g. fingers and toes and wash after 8-10 hours for permethrin or 24 hours for malathion
Wash all towels, sheets etc.
Reapply if removed during the day e.g. hand washing or nappy change.
Repeat treatment after 7 days
Treatment may worsen itch in first 2 weeks
What is the difference between nits and lice?
Lice are the insect; nits are the eggs. Also known as Pediculosis capitis.
How do nits/lice present?
Usually asymptomatic, presents due to lice being seen
Itch and rash on nape of neck
Head lice are spread by direct head-to-head contact and therefore tend to be more common in children because they play closely together. They cannot jump, fly or swim! When newly infected, cases have no symptoms but itching and scratching on the scalp occurs 2 to 3 weeks after infection. There is no incubation period.
How are headlice managed?
2 applications 7 days apart of Malathion, then shampoo and rinse + fine toothed combing
Dimectome and Isopropyl myristate and cyclomethicone are alternative (last two not suitable in under 2s or with skin conditions)
School exclusion not required nor treatment of household contacts
Treat crab lice – sexually transmitted in the same way
What is a dermatophyte infection?
This is also known as ringworm or tinea followed by the part of the body it affects e.g. tinea pedis (athlete’s foot), cruris (groin), capitis, unguium (nail) and corporis (body). It is a fungal infection that invade and grow in dead keratin. Spread is indirectly via person to person.
What causes dermatophyte infections?
The most common cause is usually human only e.g. Trichophyton rubrum.
Species that also infect animals tend to induce more inflammation such as Microsporum gypseum.
How does ringworm present?
Round, scaly, itchy, lesion
Edge more inflamed than the centre
In children can cause a scarring alopecia
If left untreated will form into a Kerion
How should ring worm be investigated?
Send samples e.g. scalp scraping for microscopy
How is ring worm managed?
Generally oral antifungal e.g. terbinafine, imidazole or fluconazole twice daily for 2 weeks – 4 weeks
Where does candida most commonly infect?
Most commonly infects, skin folds, mouth, vagina, glans penis, toe web and nail areas.
What is candida intertrigo and how does it present?
Candida Intertrigo (skin folds) Appears as erythematous and macerated plaques with peripheral scaling associated with moist pink satellite papules or pustules. In hot damp skin folds such as under the breast or under abdominal fat folds, arm pits and groin and webbed spaces between fingers and toes.
How does oral candida present?
White patches seen on the gums, tongue and inside the mouth, they can be peeled off leaving a raw area.
How is candida treated in different locations?
Skin – clotrimazole cream or if severe oral such as fluconazole
Mouth – oral nystatin or miconazole gel. Can also get antifungal mouthwashes e.g. Triclosan
Vagina – imidazole cream and/or pessary
What is pityriasis versicolor?
Also known as tinea versicolor is a superficial cutaneous fungal infection caused be Malassezia which results in multiple hypopigmented, white or brown scaly macules on the upper trunk and back. They produce an acid that prevents tanning and can be itchy.
What are the risk factors for pityriasis versicolor?
Usually healthy individuals
Immunosuppression
Malnutrition
Cushing’s
How is pityriasis versicolor managed?
Treat with ketoconazole shampoo as is most effective for large areas.
If failure to respond, consider alternate diagnosis and give oral itraconazole.
What is impetigo?
Contagious superficial infection caused to staph aureus and sometimes strep pyogenes. Usually seen in kids 2-5yrs either as a primary infection or a complication of an existing skin condition.
